It will be described with reference to FIG. 9 and FIG. 10. FIG. 9 is a configuration view of a seat, and FIG. 10 is a side view of a reclining device of the seat for a vehicle of the prior art.
As shown in FIG. 9, a seat 101 includes a seat cushion 102 supporting buttocks of a seated person, and a seat back 103 provided to be tiltable with respect to the seat cushion 102 in a forward and rearward direction and to support a back of the seated person. Reference numeral 104 is a reclining device provided on a rotational axis of the tilting of the seat back 103 to allow and restrict the tilting of the seat back 103.
The reclining device 104 will be described with reference to FIG. 10. In the drawing, a hinge pin 131 is provided to stand on a lower arm plate (second member) 130, which is attached to a rear portion of a lower arm provided at a seat cushion side. A ratchet plate (first member) 132 is rotatably arranged on the hinge pin 131 and is fixed to an upper arm provided at a seat-back side. A lower portion of the latchet plate 132 is provided with internal teeth 133 in a circumferential direction of a circle centered on the hinge pin 131.
A pawl 134 is arranged between the lower arm plate 130 and the latchet 132, and it is formed with external teeth 135 which can be engaged with the internal teeth 133 of the latchet plate 132.
The lower arm plat 130 is provided with guides 136 and 137 for guiding the pawl 134 in a radial direction of a circle centered on the hinge pin 131.
A release arm 142 rotatably installed in the hinge pin 131 is formed with a elongate hole 143, into which a pin 140 of the pawl 134 penetrating an arc-shaped elongate hole 132e which is formed in the latchet plate 132 and centered on the hinge pin 131 is fitted. The elongate hole 143 is configured to have a portion close to the internal teeth 133 of the latchet plate 132, and a portion spaced apart from the internal teeth 133, and when the release arm 142 rotates, the pawl 134 moves in the radial direction of the circle centered on the hinge pin 131, and then the external teeth 135 of the pawl 134 is engaged with or disengaged from the internal teeth 133 of the latchet plate 132.
A first cam 144 is rotatably attached to the hinge pin 131.
A second cam 141 is provided between the first cam 144 and an inclined face of the pawl 134, which is opposite to its side formed with the external teeth 135. The inclined face of the pawl 134 is a face intersecting with the radial direction of the circle.
The release arm 142 is applied with an urging force by a spring 150 in such a direction that the first cam 144 presses the pawl 134 via the second cam 141, and the spring 150 has one end portion locked to the release arm 142 and the other end portion locked to the lower arm plate 130.
An end face of the hinge pin 131 is formed with a groove, and an inner end portion of a spiral spring 156, of which an outer end portion is locked to the pin 155 provided to stand on the latchet plate 132, locked to the groove, so that the latchet plate 132 (upper arm) is urged in a forward tilting direction.
Next, the operation of the configuration will be described. The state shown in FIG. 10 is a state where the first cam 144 presses the pawl 134 via the second cam 141 which contacts the inclined face of the first cam 144, the guide 137, and the pawl 134, respectively, and the external teeth 135 of the pawl 134 are engaged with the internal teeth 133 of the latchet plate 132 to restrict the rotation of the latchet plate 132, so that the reclining (tilting) of the seat back is locked and.
In this state, when the release arm 142 located at a position indicated by a solid line is rotated to a position indicated by a two-dot chain line against the urging force of the spring 150, the first cam 144 engaged with the release arm 142 is rotated in the same direction, and thus the state of pressing the pawl via the second cam 141 of the first cam 144 is released.
The pawl 134 having the pin 140 which is fitted into the elongate hole 143 of the release arm 142 is also guided by the guides 136 and 137 to move in the direction of the hinge pin 131, and thus the engaging state of the external teeth 135 of the pawl 134 and the internal teeth 133 of the latchet plate 132 is released, so that the latchet plate 132, i.e. the seat back, is to be in a tiltable state.
When the seated person achieves a desired tilting angle by tilting the desired seat back, one releases the operation force of the release arm 142. Then, the release arm 142 is returned from the position indicated by the two-dot chain line to the position indicated by the solid line by the urging force of the spring 150, and the first cam 144 is rotated in a direction contrary to the above-described direction to be returned in the state in FIG. 10 (e.g., see Patent Document 1).